I would like to stream some movies with downloaded subtitles from my hard drive to my IPad mini.
What are some ways I can achieve that solution?
I use Ubuntu 15.10 or Windows and my IPad is updated with the last iOS.
Looks like VLC Player is the best option for you right now in regards to subtitles on iOS devices.
The site http://www.iphonehacks.com/2014/01/vlc-tips-tricks.html states:
"VLC also includes support for subtitles. Some video formats natively support subtitles while for others, you need a separate .sub file. If you need to add a separate .sub file, name it similar to the video filename, and add it to VLC for iOS via any of the file transfer means described above. VLC will automatically associate the two and show you subtitles."
VLC, on Mac, Windows, and iOS, is as flexible as it gets when it comes to video players, so you can't go wrong with it. It also allows you to wirelessly transfer video from your PC to the app, allowing you to bi-pass iTunes and WMA, which is always a plus ;).
Hope that helps!